on Method Basics
on Method Basics: free step-by-step lesson with examples, common mistakes, and interview tips — part of jQuery Tutorial on Toolliyo Academy.
On this page
jQuery Tutorial · Lesson 27 of 100
on Method Basics
Setup & DOM ✓ → Events Effects AJAX → Perf & Integrate → Ship & Projects
Events Effects AJAX · 2 — Interact · ~6 min · Events
What is this?
on(events, handler) is the core binding API. Pass multiple events as a space-separated string. Namespaces like click.qvHelp group handlers for later off().
Why should you care?
Modern QueryVerse code standardizes on .on instead of mixing .click/.bind/.live.
See it live — copy this example
Examples include the jQuery 3.7 CDN. Paste into an HTML file or use Run Example to preview.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>QueryVerse</title>
<style>
body { font-family: system-ui, sans-serif; margin: 1.25rem; }
.box { padding: .75rem; border: 1px solid #ccc; border-radius: 8px; margin: .5rem 0; }
.muted { color: #666; }
button { margin-right: .35rem; margin-top: .35rem; }
input, select, textarea { margin: .25rem 0; }
table { border-collapse: collapse; width: 100%; }
th, td { border: 1px solid #ddd; padding: .4rem .55rem; text-align: left; }
.hidden { display: none; }
.row-odd { background: #f7f7f7; }
.active { font-weight: 700; }
.toast { background: #111; color: #fff; padding: .5rem .75rem; border-radius: 6px; }
</style>
</head>
<body>
<button type="button" id="save">Save</button>
<button type="button" id="help">Help</button>
<p id="out" class="muted"></p>
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
<script>
$(function () {
$('#save').on('click.qv', function () {
$('#out').text('saved via on');
});
$('#help').on('click.qv mouseenter.qv', function (e) {
$('#out').text(e.type + ' on help');
});
});
</script>
</body>
</html>
Run Example »
Edit the code below and click Run to see the result in Toolliyo’s live editor.
What happened?
- Handler receives the event object.
- this is the DOM element (use $(this) for jQuery).
- Bind after nodes exist or use delegation.
Practice next
- Click Save and Help.
- Hover Help to see mouseenter.
- Inspect namespaces in your mental model for off later.
- Add e.preventDefault on a link with .on("click").
- Pass event data: .on("click", {id:1}, fn).
Remember
.on is the standard binder. Namespaces organize handlers. this = element.
Toolbar wiring
A Zoho Books QueryVerse toolbar binds Save/Help with namespaced .on handlers.
Outcome: One style of binding for every control on the page.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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